The method to make a choppy golf shot and get your golf ball out of deep grass or rough.

[edit] Steps

Choose a 7-iron or a wedge.
Take an open stance. Always aim to the fairway or green. The ball lies more towards the back foot. Weight is on your front foot.
Use your normal golf grip. Choke your hands down a little bit.
Aim your feet to a point left of a target on the fairway or green. The grooves are square to the ball. An open golf club face will help you to generate more loft.
Swing your club backwards - 3/4 of a normal golf swing. Turn your shoulders and hips for more power and speed. Hinge your wrists a little bit, just like you are making a fine pitching shot. But not too much.
Get Out of the Rough

Accelerate when you hit the club down, and hit through the grass. The down swing has to be powerful enough to help the ball out of the rough.
Chop the ball with many swing speed - like you make a bunker golf shot.
Swing through and point your golf club towards the target

[edit] Tips

Keep your hands firm while approaching the ball, because the golf club face must stay open at impact.
Don't look up too early after you hit the ball in the rough!